Submission to the State Development, Infrastructure And
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Submission to the State Development, Infrastructure and Industry Committee Inquiry “Queensland Audit Office Report to Parliament 14 for 2012- 13: Maintenance of water infrastructure assets” School of Civil & Environmental Engineering Date: 18 October, 2013. Author: Dr Stuart Khan Address: School of Civil Environmental Engineering, University of New South Wales. Phone: (02) 93855070 Email: [email protected] Table of Contents EXECUTIVE SUMMARY 2 BACKGROUND 3 INTRODUCTION 4 CURRENT OPERATIONAL STRATEGY FOR THE WCRWS 5 PROPOSED OPERATIONAL STRATEGY FOR THE WCRWS 7 DESCRIPTION OF PROPOSED OPERATIONAL STRATEGY 7 ADVANTAGES OF PROPOSED OPERATIONAL STRATEGY 7 IMPROVED AND PROTECTED RAW WATER QUALITY FOR THE MT CROSBY WATER TREATMENT PLANT 7 DIVERSIFICATION OF SOURCE WATER OPTIONS FOR THE MT CROSBY WATER TREATMENT PLANT 9 REDUCED WATER PUMPING REQUIREMENTS 9 AN OPPORTUNITY TO INCREASE FLOOD MITIGATION CAPACITY 9 DIRECT POTABLE REUSE (DPR) 11 WHAT IS DIRECT POTABLE REUSE (DPR)? 11 FINDINGS BY THE ACADEMY OF TECHNOLOGICAL SCIENCES AND ENGINEERING (ATSE) 12 CONCLUDING COMMENTS 14 REFERENCES 15 Executive Summary This document is presented as a public submission to the State Development, Infrastructure and Industry Committee of the Queensland Parliament Legislative Assembly inquiry into the issued contained in the Queensland Audit Office Report to Parliament 14 for 2012-13: Maintenance of water infrastructure assets. The focus of this submission is the configuration and operation of the Western Corridor Recycled Water Scheme in relation to the operation of Lake Wivenhoe as the major water supply reservoir for South East Queensland. This submission specifically addresses key aspects of the Inquiry Terms of Reference including: “innovative strategies to increase revenue from manufactured water infrastructure assets” and “the future public value of the assets including consideration of the impact on the community, economy and environment”. The current operational strategy of the WCRWS is briefly summarised to provide clear context for the central proposal of this submission. An alternative, considerably more advantageous, operational strategy for the WCRWS is then proposed as follows: 1. Construct a new pipeline from the Bundamba AWTP to the Mt Crosby Water Treatment Plant. This would enable water from the three AWTPs to be directly transferred to Mt Crosby for potable use. 2. Reverse the flow of water in the pipeline from the Bundamba AWTP to the “Possible release to Wivenhoe” point. That is, reservoir water from Lake Wivenhoe would be transported in a protected enclosed pipeline to Bundamba. It would then be transferred from Bundamba to Mt Crosby via the new pipeline proposed above. 3. Decommission the section of the pipeline from the “Possible release to Wivenhoe” point to the Tarong Power Station off-take. It is far less energy intensive for the Tarong Power Station to source water from the north-western reaches of Lake Wivenhoe. Outcomes of the proposed alternative WCRWS configuration are described, including the following: Improved and protected raw water quality for the Mt Crosby Water Treatment Plant Diversification of source water options for the Mt Crosby Water Treatment Plant Reduced water pumping requirements An opportunity to increase flood mitigation capacity It is proposed that there are a broad range advantages to be realised from these outcomes. These include opportunities for improved raw water supply, increased flexibility, significantly increased system resilience, reduced operational costs, reduced energy consumption and greenhouse footprint, and improved mitigation of future flooding events. An essential aspect of this proposed alternative configuration is known as ‘direct potable reuse’ (DPR) of highly treated recycled water. A brief overview of the concept of DPR is provided, along with the relevant finding of a recent report from the Australian Academy of Technological Sciences and Engineering (ATSE). 2 Background On 7 June 2013, the State Development, Infrastructure and Industry Committee of the Queensland Parliament Legislative Assembly referred the Queensland Audit Office Report to Parliament 14 for 2012-13: Maintenance of water infrastructure assets to the committee for consideration. The Queensland Audit Office report examined whether the South East Queensland Water Grid assets, namely the Gold Coast Desalination Plant and Western Corridor Recycled Water Scheme are being managed and maintained effectively to contribute to a secure and sustainable water supply. In accordance with Section 94 of the Parliament of Queensland Act 2001, the committee has resolved to undertake an inquiry into the issues contained in the Queensland Audit Office Report. The Terms of Reference for this inquiry state: “In conducting its inquiry, the committee will: examine the issues contained in the Queensland Audit Office Report to Parliament 14 for 2012-13: Maintenance of water infrastructure assets consider the value for money of manufactured water infrastructure assets: o operating and maintenance costs of manufactured water infrastructure assets o innovative strategies to increase revenue from manufactured water infrastructure assets o the future public value of the assets including consideration of the impact on the community, economy and environment consider the policy framework for decisions to invest in significant bulk water supply infrastructure, or to upgrade current infrastructure.” This document was prepared as a submission to this inquiry. It addresses the terms of reference as described in the following section. 3 Introduction This submission specifically addresses key aspects of the Inquiry Terms of Reference including: “innovative strategies to increase revenue from manufactured water infrastructure assets” and “the future public value of the assets including consideration of the impact on the community, economy and environment”. No financial determinations regarding “value for money” are provided in this submission. However, an innovative operational strategy for the Western Corridor Recycled Water Scheme (WCRWS) is identified. This strategy has the potential to significantly increase the benefits derived from of the operation of the WCRWS, while concurrently lowering the operational costs. 4 Current operational strategy for the WCRWS The WCRWS was constructed in accordance with the schematic illustration provided in Figure 1. The key features include: Advanced water treatment plants (AWTPs) o Luggage Point AWTP o Gibson Island AWTP o Bundamba AWTP Water transfer pipelines o Luggage Point AWTP to Gibson Island AWTP to Bundamba AWTP o Bundamba AWTP to Swanbank Power Station o Bundamba AWTP to Tarong Power Station connection o “Possible release to Wivenhoe” pipeline In this arrangement, water is required to be pumped a considerable distance (east to west) from the AWTPs to the Tarong Power Station connection. This is despite the fact that the Tarong Power Station connection is adjacent to an alternative available local water supply (the north-western reaches of Lake Wivenhoe). If this arrangement were to be used for its full intended purpose, including indirect potable reuse (IPR), water would also be pumped (east to west) from the AWTPs to Lake Wivenhoe. This highly purified water would then be mixed with lower-quality environmental water, before returning back down the Brisbane River to the Mt Crosby Water Treatment Plant. This is an energy-intensive (and hence expensive) exercise in pumping water uphill, in order to allow it to flow back down again. In doing so, the water is exposed to environmental contamination, as well as environmental losses such as by evaporation. 5 Figure 1 Schematic illustration of the WCRWS (Gardner & Dennien, 2007). 6 Proposed operational strategy for the WCRWS A proposed alternative operational strategy for the WCRWS is described below. This alternative strategy involves only minimal additional capital construction (a pipeline between Bundamba and Mt Crosby) and offers a range of highly beneficial advantages to drinking water suppliers and customers in South East Queensland. Description of proposed operational strategy A considerably more advantageous operational strategy for the WCRWS is described in the following points: 4. Construct a new pipeline from the Bundamba AWTP to the Mt Crosby Water Treatment Plant. This would enable water from the three AWTPs to be directly transferred to Mt Crosby for potable use. 5. Reverse the flow of water in the pipeline from the Bundamba AWTP to the “Possible release to Wivenhoe” point. That is, reservoir water from Lake Wivenhoe would be transported in a protected enclosed pipeline to Bundamba. It would then be transferred from Bundamba to Mt Crosby via the new pipeline proposed above. 6. Decommission the section of the pipeline from the “Possible release to Wivenhoe” point to the Tarong Power Station off-take. It is far less energy intensive for the Tarong Power Station to source water from the north-western reaches of Lake Wivenhoe. Advantages of proposed operational strategy There are a broad range advantages to be realised from the alternative operational strategy. These include opportunities for improved raw water supply, increased flexibility, significantly increased system resilience, reduced operational costs, reduced energy consumption and greenhouse footprint, and improved mitigation of future flooding events. These advantages are described below. Improved and protected raw water quality for the Mt Crosby Water Treatment Plant